A growing portion of the television programming that is viewed by Americans is broadcast directly to home receivers by geosynchronous satellites. These satellites operate in orbits positioned above the Earth's Equator at an altitude of approximately 22,300 miles. Some consumers use relatively large satellite dishes that may be ten or more feet in diameter to receive television programming directly from satellites such as the Galaxy.TM. and Telstar.TM. series of spacecraft. In the past year, receivers that employ much smaller antennas that are only about two feet across have been introduced in the United States. These newer and smaller systems obtain signals from powerful new satellites operated by DirecTV.TM. and USSB.TM..
One unfortunate consequence of relying on direct broadcast systems is that they rarely, if ever, provide programming from local stations. One possible solution to this problem would be to use high-altitude airplanes to rebroadcast local television stations in the same frequency band used for direct satellite television broadcasting. The satellites that supply direct broadcast signals move in orbits that are synchronized with the rotation of the Earth. A given geosynchronous satellite therefore appears to be in almost exactly the same elevation and azimuth for all viewers in even a large metropolitan area. In contrast, because the airplane is at a much lower altitude than the geosynchronous satellites used for television broadcasting, it cannot be at the same angle for all viewers.
The problem with this approach is that two different antennas would then be required--one for signals emanating from the satellite, and a second oriented to the airplane's position for signals emitted from the aircraft. The viewer would not only be faced with the higher cost of purchasing two different antennas, but would also suffer the inconvenience of having to constantly switch between the two antennas each time he or she wishes to change channels that are not supplied solely by either the satellite or the aircraft.
Other previous attempts to offer broadcast services from a variety of platforms have been met with mixed results. A number of systems are described in the U.S. Patents cited below.
U.S. Pat. No. 4,392,139, issued to Aoyama et al. in 1983, discloses an omni-directional VHF television antenna system for an aircraft.
U.S. Pat. No. 4,218,702, issued to Brocard et al. in 1980, describes a means for remote control of an aircraft video system for surveying ground activity.
U.S. Pat. No. 3,972,045, issued to Perret in 1976, pertains to an apparatus for transporting and entertaining passengers aboard an aircraft with a television system.
U.S. Pat. No. 3,778,007, issued to Kearney, II et al. in 1973, concerns a rod television-guided drone to perform reconnaissance and ordnance delivery.
U.S. Pat. No. 3,406,401, issued to Tillotson in 1968, discloses a synchronous satellite communication system for communicating simultaneously with a number of ground stations.
U.S. Pat. No. 2,748,266, issued to Boyd in 1956, describes a radiant energy relay system having mobile relay signaling stations moving in continuously progressing succession.
U.S. Pat. No. 2,626,348, issued to Nobles in 1953, relates to radio systems employing equipment mounted on aircraft for re-transmitting or relaying programs.
U.S. Pat. No. 2,598,064, issued to Lindenblad in 1952, discloses the transmission of radio signals between remote points.
U.S. Pat. No. 2,509,218, issued to Deloraine in 1950, pertains to a radio multi-channel communicating system adapted for association with predetermined routes.
U.S. Pat. No. 4,253,190, issued to Csonka in 1981, describes a communications system using a mirror kept in outer space by electromagnetic radiation pressure.
U.S. Pat. No. 5,133,081, issued to Mayo in 1992, discloses a remotely controllable message broadcast system including central programming station, remote message transmitters and repeaters.
This problem of designing a system which provides programming from both satellites and local sources without utilizing two different antennas has presented a major challenge to the satellite business. The development of a home receiver that is capable of supplying both local and satellite signals but which is also relatively inexpensive and easy to use would constitute a major technological advance and would satisfy a long felt need within the television and communications industries.